The present invention relates generally to laser surgery probes, and particularly to probes having contact tips which are heated by laser energy.
Contact tips are commonly used in laser surgery for a variety of procedures, including surgical incisions and coagulation. Typically, such contact tips comprise a tip body of a transparent material such as sapphire which is capable of withstanding high temperatures. The sapphire may be coated with a coating that is absorptive to laser energy. Absorption of the laser energy heats the tip to high temperatures suitable for tissue vaporization. One problem with such tips, however, is that they do not distribute the laser energy evenly and thus heating is not uniform. Further, due to toxicity or other adverse effects of the coating, an overcoat of, for example, ceramic or glass, must be applied to prevent the coating from contacting the tissue. Examples of contact tips utilizing absorptive coatings are disclosed in U.S. Pat. Nos. 4,736,743 and 4,832,979.
Typically, contact tips receive laser energy from a waveguide, such as an optical fiber. Laser light propagates out of the waveguide end through an air gap and strikes an input face of the contact tip. The input face is generally normal to the axis of propagation. Because the indices of refraction between the waveguide, the air gap and the contact tip material do not match, some radiation is reflected from the input face, resulting in build up of thermal energy.
When operating with laser surgery contact probes, surgeons use a variety of tip shapes, depending on the type of incision or degree of coagulation required. Typically, contact tips configurations are conical, hemispherical, flat or chisel-shaped, and a complete set of tips can be expensive. Moreover, the inconvenience of changing a tip and the time involved in doing so is a disadvantage to tactile laser surgery.
Surgeons further have difficulty in using contact tips in confined areas, particularly in tight endoscopic environments. Because of the confined surgical site, inadvertent contact with healthy tissue often occurs resulting in undesired thermal damage.